(one) leaf; (one) petal; piece (of paper); flake (of snow)
「一片」 has another reading with different meanings.
桜の一枚が風に乗って手のひらに落ちた。
A cherry blossom petal rode the wind and fell onto my palm.
一枚の花びらが水面に浮かんでいる。
A single petal is floating on the water's surface.
秋風に吹かれて紅葉が一枚ずつ散っていく。
Blown by the autumn wind, the leaves scatter one by one.